Model test of the surface and submerged vehicles with the micro-bubble drag reduction

This study is based on the effective experiment observation and measuring technology to discuss the interaction influence between liquid turbulent boundary layer and a crowded group micro-bubbles. It is in order to understand and quantify the micro-bubbles clouds inside the turbulent boundary layer to eliminate the capacity of skin friction drag. Whenever the micro-bubbles are over supplied, pile up effect happened which makes micro-bubbles to integrate to each other as a large-size air film. Although they still have the drag reduction effect, the efficiency of drag reduction slowed down at this transition period. In the experiment of vertical type circulating water tunnel, when 1 μm porous medium is at 7 m/s flow speed, the Cv value at 0.056 has the best drag reduction efficiency of 26%. While 10 μm porous medium is at the same flow speed, the drag reduction efficiency is only around 23%.